The present invention relates to a pin for disposition between adjacent slash faces of turbine bucket platforms and particularly relates to a system for damping bucket vibrations and cooling the slash faces of turbine bucket platforms to temperature levels required to meet part life requirements including oxidation, creep and low cycle fatigue cracking.
Over the years gas turbines have trended towards increased inlet firing temperatures to improve output and engine efficiencies. As gas path temperatures have increased, bucket platform slash faces have increasingly exhibited distress including oxidation, creep and low cycle fatigue cracking. This effect is magnified in turbines where closed loop cooling is utilized because film cooling in upstream nozzles is significantly reduced or eliminated producing higher gas path temperatures at the bucket platforms. Distress of the bucket platform slash faces can damage the platform and cause loss of damping leading to aeromechanics failure, liberation of the platform causing damage to other turbine components, and compressor discharge flow leakage leading to reduced engine efficiency.
It will be appreciated that many prior turbine designs did not require active cooling of the platform slash faces due to lower firing temperatures and film cooling carry over from upstream nozzle side walls. Consequently there has developed a need to reduce the platform slash face temperatures to a level required to meet part life requirements particularly in view of the higher firing temperature of present day gas turbines.